LA Metabolic Dx 2 - Macromineral Flashcards
Hypocalcaemia - Aetiology
Maintenance:
- Increase DMI → Increase Ca
requirement
- 10kg DMI → ~ 15g/day
- 25Kg DMI → ~ 30g/day
Lactation:
- ~ 2g Ca per litre of milk
Ca Homeostasis
Low Ca = Increase PTH
Increase Ca mobilisation
More Ca absorbed in kidneys
More Ca absorbed from bone and GIT
Dietary Cationic Anionic Difference (DCAD)
([Na+] + [K+]) – ([Cl-] + [S2-])
Low DCAD = acidosis
High DCAD (>100mEq/kg DM) = alkalosis
Hypocalcaemia Risk Factors
Cow Factors
- Increase yield
- Increase age
- Previous hx
- Breed = dairy
- Genetic
Precalving Nutrition
- Increased DCAD
- Inadequate priming
- Increase Ca
- Decrease Mg
Hypocalcaemia - Clinical Signs
4 points
Skeletal:
- Weak
- Ataxia
- Recumbency
- S-bend neck
Smooth:
- Inappetent, ruminal
hypomotility
- Ruminal tympany
- Constipation
Cardiac:
- Compensatory tachycardia
Other Signs:
- Depression
- Dry muzzle
- Hypothermia
- Cold extremities
- Coma
- Death
Hypocalcaemia - Subclinical Signs
↓ repro performance
- ↑ Uterine inflam dx
- ↓PR & ↑ empty days
↑ metabolic dx
- Ketosis / Fatty liver
- Abomasal displacements
↓ production
- ↓ Yield
- ↓DMI
↓ Immunity
- ↑ PP infectious dx
Hypocalcaemia - Diagnosis and Management
Diagnosis:
- Clinical signs
- Serum biochem
Tx:
- IV Ca borogluconate
- Oral Ca
- Nursing & nutrition
- Manage 2° conditions
Hypocalcaemia - Prevention
Ca restriction
Low Ca intake
- <20g/d
Feeding strats
- Grass/ silage high in Ca
- Dilute Ca - increase straw
Hypocalcaemia - Prevention
Mg Supplements
Increase Ca mobilisation
Feeding strats
- MgCl2 in TMR/ drinking water
- Affect ration palatability
Hypocalcaemia - Prevention
DCAD Manipulation
Metabolic acidosis →
- Vit D3 activated per unit PTH
- Target tissues = more sensitive
to PTH and 1,25(OH)2D3
- More rapid Ca mobilisation
around calving
Feeding Strats
- Full DCAD – add Anionic Salts
- Partial DCAD - decrease grass
silage and increase maize
silage/ straw
Hypocalcaemia - Sheep
- Last trimester
- Dull depressed
- Inappetent/ anorexia
- Normal vision
- No rumen contractions
- Ataxic
- Recumbent
- Severe resp signs
- BHBs normal
- IV Ca = rapid response
Pregnancy Toxaemia - Sheep
- Last trimester
- Dull depressed
- Inappetent/ anorexia
- Bilateral central blindness
- Reduced rumen contractions
- Ataxic
- Recumbent
- No resp signs
- BHBs increased
- IV Ca = prolonged response
Hypomagnesaemia = Staggers
Aetiology
Daily Requirements
- ~3g = milk
- ~2.5g lost in urine
Reserves
- Blood stream = 5.5g
- From bone = 0.5g
Diet
- 5g/d min
Hypomagnesaemia - Risk Factors
3 points
Decreased DMI
- Disease (Lameness, dental)
- Physiological conditions
(Calving, Oestrus)
- Inclement weather or
inadequate shelter
Decreased Mg in Feed
- Rapid grass growth
- Season
- Inadequate supplements
- Poor quality feed
Increased Demand
Hypomagnesaemia - Signs
- Nervous, excitable,
hyperaesthesia - Muscle tremors
- Bruxism, froth at mouth
- Ataxia (staggering gait) &
collapse - +/- Convulsions & seizures
- +/- Pyrexia
- Sudden death
Hypomagnesaemia - Diagnosis
- Clinical signs
- Serum Mg levels
- PM (Mg increases PM)
- CSF
- Aqueous humour (<24hrs
dead) - Vitreous humour (>24hrs
dead)
Hypomagnesaemia - Mx
» +/- Sedation (IV / IM Xylazine)
- Seizures / convulsions
- Prevent injury
- H&S
» Mg supplement
- SLOW IV: 100ml MgSO4 in
300ml Ca BG 20%
- SC: 400ml MgSO4
- Warm 1st
Hypomagnesaemia - Prevention
Mg supplementation
- Boluses
- Concentrates
- Lick buckets
Improve Mg sward content
Buffer feeding
Decrease fertiliser usage
Shelter
Monitor
Hypophosphataemia
» Clinical syndromes
- Periparturient
haemaglobinuria
- (Downer cow, post
hypocalcaemia)
» Diagnosis
- Clinical signs
- Serum biochemistry
» Management
- Foston (Toldimphos)
